Scientific Events

Speaker: Dr. Tobias Brink

Molecular dynamics simulations and beyond for plasticity and wear of metals

Molecular dynamics simulations and beyond for plasticity and wear of metals
While the general principles underlying the plastic response of metals are mostly understood—especially for the crystalline state—advanced tailoring of their properties and the development of novel, high-performance materials requires detailed insights into the mechanisms at the atomic scale. This talk will discuss how computer models and simulations can be the tools of choice to discover such mechanisms in the context of our work on amorphous metals and wear. I will first introduce some concepts of molecular dynamics computer simulations and how we used them to investigate the plastic deformation of metallic crystal/glass composites, where localized and collective shear transformations govern the macroscopic behavior. In particular, I will address the questions of when and how precipitates can enhance the mechanical properties of metallic glasses and what the difference between a nanocomposite and a nanocrystal is. In the second part, I will discuss our current work on wear of materials and what to do when the time and length scale limitations of molecular dynamics become a problem. When surfaces in contact slide relative to each other, they are in fact only in contact in some small areas due to their roughness. At this length scale, we employ molecular dynamics with different model materials in order to elucidate how detachment of matter occurs in the form of individual particles, which in the end comes down to the details of nanoscale plasticity and fracture processes. In order to gain insights on relevant figures of merit for applications, though, we have to collect statistics of wear particle formation at the meso to macroscale, using continuum methods. Since some of this work is in its early stages, I will finish the talk with a preview of promising future research directions and methods, such as taking the microstructure evolution of the material into account. [more]
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